Currently, touch-screen terminals are used most frequently. However, when a user makes a phone call via such terminal, the terminal may be mis-operated due to a long-time contact between the screen of the terminal and the user's face or head. In the related technology, the problem is generally solved by using optical sensing technology to control the screen to be on and off, the principle of which is to sense the peripheral light condition with an optical sensor, and then inform a processing chip of a controller in the terminal to turn the screen on or off. During the calling process, the optical sensor at the front of the terminal senses the peripheral light condition. When the terminal gets close to a human body (such as ear) within a certain distance, the optical sensor senses that the light turns dark, so the controller turns off the screen. When the terminal gets away from the human body for a certain distance, the optical sensor senses that the light turns bright, so the controller turns on the screen.
However, the optical sensor lacks a measurable standard to determine the sensed light condition of the peripheral light, and the sensed condition is easy to be affected by the light intensity of the environment around the terminal. As a result, it is difficult to control the screen to be on and off precisely.